Implants are now commonly used for providing anchor points in the jaw to which supports are made for a single tooth, for multiple teeth, for bridges and/or for prosthetic devices. If more than one implant is to be installed in the jaw or if implants are to be used in combination with existing non-implant appliances, it is highly desirable that all the implants be parallel with each other. This parallelism makes for precise and uniform angulation of implants in the jaw and also provides precise abutments in anchor teeth for bridges and the like.
Several attempts in have been made in the prior art for obtaining a paralleling device. For example a device consisting of two arms, wherein one arm is attachable to an anchor means whereas the other arm is used to guide the burr for drilling the necessary holes. The burr is typically led through a bore in the other arm. It is however difficult to obtain a precise parallel alignment with the anchor means when the burr is led through a bore in the arm since some tolerance is necessary for the burr to be able to perform the relevant drilling action. Furthermore, the device requires that only burrs of a certain diameter are acceptable, namely those fitting into the bore of the arm.
U.S. Pat. No. 5,302,122 discloses a dentistry implant paralleling device consisting of several identical shaped links capable of being pivotably connected for forming a chain. Furthermore, one of the links may be connected to a dentist handpiece and a link at the other end of the chain may be attached to an anchor means in the jaw. By the use it is possible to drill a hole in the jaw parallel to the anchor means. It is however not possible to correct for the different height levels in the jawbone when drilling. Furthermore, due to the several links necessary to provide the relevant movements some uncertainty with respect to the parallelism of the holes remains, since it is not possible to design the releasable links without marginal tolerances. This is also the case in DE 37 30 055 describing an instrument for parallelly directing a dentist's burr. The instrument consists of three links, connected so that the links cannot be vertically moved in relation to each other during use of the instrument, and in DE 19 60 394 describing an instrument for parallelly directing a dentist's burr. The instrument consists of two telescopic arms connected through a cardan joint. In another reference, U.S. Pat. No. 5,741,133, an instrument for parallelly drilling holes for dental implants, wherein the instrument has one arm, is described. This provides a better stability, but does also lead to an undesirably low mobility of the instrument in use.